Surface mount carrier tape is used to transport components (e.g., electrical components such as resistors, capacitors, or integrated circuits) from a component manufacturer to a different manufacturer or assembler that assembles the components into new products such as into circuit boards, typically by having automated assembly equipment sequentially remove components from the carrier tape and assemble them into the new products. Such carrier tape is a strip of material that has a series of identical pockets at predetermined uniformly spaced intervals along its length, which pockets are shaped to closely receive components the tape is adapted to transport (e.g., which pockets could, for example, have rectangular or generally "I" or "T" shapes in the plane of the strip). The strip normally also has through openings uniformly spaced along one side to receive a drive sprocket by which the strip can be driven and to provide indexing holes that can be used for accurately locating the pockets along the tape with respect to assembly equipment. Typically, the carrier tape is manufactured in a first manufacturing location, wound on a reel and transported to the supplier of the components it is intended to transport. The component supplier unwinds the carrier tape from the reel, fills the pockets along the carrier tape with components, adheres a removable cover strip along the carrier tape over the component filled pockets, winds the component filled carrier tape with the attached cover strip onto a reel, and sends it to the component assembler who feeds it from the reel into the assembly equipment which removes the components.
One common type of such carrier tape called embossed carrier tape, illustrated in U.S. Pat. No. 4,736,841, is typically formed from an initially flat polymeric heated thermoplastic strip using a tool to deform portions of the strip and form the pockets (e.g., male and female die sets, or a male or a female die over which the strip is vacuum formed). Although this carrier tape is termed embossed, it appears to have been made by thermoforming, e.g. vacuum thermoforming. The receiving concavities 17 as shown, for example in FIG. 2 of this reference, protrude from receiving sheet 15. This is a construction reflective of vacuum forming. This construction has the disadvantage that the protruding concavities, are subject to crushing as the sheet is tightly wound on a reel. In the embodiments shown in FIGS. 8 and 12 the receiving sheet 24 is formed with through-holes 25. Holes 25 penetrate entirely through sheet 24 and thus a bottom tape 26 is required to cover the bottom of the concavities in order to keep the electronic components from falling out.
A less expensive type of such carrier tape called flat punched carrier tape, illustrated in U.S. Pat. Nos. 4,298,120 and 4,657,137, is typically formed by die punching a series of openings of a desired shape for the pockets through a strip slit from a sheet of material having a thickness corresponding to the depth of the pockets to be formed. The die punched pockets are through-holes and have adhering a bottom strip along one side of the punched strip to form the bottoms for the pockets. U.S. Pat. Nos. 4,724,958, and 4,406,367 and 4,760,916 similarly show pockets which go through the carrier tape and have a bottom tape to form the bottoms for the pockets.
Most strips of material used in such carrier tapes are of paper. Fine dust particles generated during slitting and punching of paper are carried by the carrier tape and deposited on the automated assembly equipment and new products of the component assembler, which can cause product quality problems. Paper has many fillers which are very abrasive to die punch tools, resulting in accelerated wear of the die and poor quality punching. Also, because of problems with delamination of layers within such paper strips, the thickness of the paper strips used in such carrier tape has been limited to about 1 millimeter (0.04 inch), which limits the size of the components that can be packaged in the carrier strip.
Strips of material used in such carrier tapes have also been made of polymeric materials which produce no dust when slit or punched. Such polymeric materials are typically filled with fillers to reduce their cost and improve the bond between existing cover tapes and the surface of such carrier tapes, which fillers make them stiffer than is desired and abrasive to die punch tools, while still being more expensive than carrier tape made with strips of paper material.
Other materials have also been suggested for the strips of material used in such carrier tapes, such as metal foils and rubber (see U.S. Pat. No. 4,298,120) and laminated polymeric foams (see U.S. Pat. No. 4,657,137); however, none has a combination of properties that provides a commercially acceptable solution to the problems discussed above.